Antibody tests don’t promise accuracy

Hyderabad: Presence of low levels of antibodies, which are measured through existing antibody tests offered by diagnostic facilities, is not an indication that one has lost protection from Covid-19. While the demand for such antibody tests has increased, especially among people who have received two doses of Covid vaccines, they do not present an accurate […]

Hyderabad: Presence of low levels of antibodies, which are measured through existing antibody tests offered by diagnostic facilities, is not an indication that one has lost protection from Covid-19.

While the demand for such antibody tests has increased, especially among people who have received two doses of Covid vaccines, they do not present an accurate picture of antibody levels generated by the body against an infection.

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Commenting on the issue of antibody tests, World Health Organization (WHO) Chief Scientist Dr Soumya Swaminathan on Sunday said, “Antibody tests do not predict protection against SARS-CoV-2 and are not recommended.”

Meanwhile, developers of SUTRA model for predicting Covid pandemic, which also includes researchers from IIT-Hyderabad, said that low levels of neutralising antibodies, detected through antibody tests, was not an indication that individuals have no protection. This is because neutralising antibodies are not the only source of protection that the body produces against the SARS-Cov-2. In fact, there are T-cell and memory B cell immunity generated by the body that also give protection against the disease.

“Antibody testing does not predict protection against SARS-CoV-2 and is not recommended. Memory B and T cells provide protection even after waning of neutralising antibodies. So far, no threshold level of antibodies has been identified,” Dr Soumya Swaminathan clarified on Twitter.

The senior researchers from SUTRA, including M Vidyasagar, SERB National Science Chair, IIT-Hyderabad, said, “Even if antibodies are negative in the tests, there are memory cells in human body that help produce antibodies when a person is confronted with the virus again”.

The cost of measuring the levels of neutralising antibodies at diagnostic centres in Hyderabad is between Rs 500 and Rs 1,000. However, the cost to measure T-cells mediated antibodies is high and there are not many diagnostic labs that offer such tests.

“Testing for T-cell mediated immunity is expensive and may cost Rs 20,000 or more, and the tests are confined to research laboratories. So far as we are aware, no private lab offers these tests, because these tests require a well-equipped research laboratory. The interpretation of such tests outside of research studies is also difficult,” SUTRA researchers clarified.

Telangana logs 105 new Covid cases

Telangana reported 105 new Covid infections and no fatality on Sunday taking the cumulative number of positive cases to 6,73,574 while the number of deaths remained at 3,973. The number of active cases in Telangana, as on Sunday, was 3,740.

The authorities today conducted 23,888 Covid tests of which results of 529 samples were awaited. A total of 106 individuals have recovered with a recovery rate of 98. 85 per cent on Sunday.

So far, a total of 2,80,50,546 Covid-19 tests have been conducted in the State out of which 6,73,574 have tested positive and 6,65,861 persons have recovered.

The Covid-19 positive cases reported from the districts included three from Adilabad, 59 from areas under GHMC, one from Jagityal, one from Jogulamba Gadwal, five from Karimnagar, one each from Khammam, Mahabubnagar, Mahabubabad and Mancherial, six from Medchal-Malkajgiri, four from Nalgonda, 10 from Rangareddy, two each from Sangareddy, Siddipet and Wanaparthy and six from Warangal Urban.

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